There are two parts on this, the ipsec client which you have on your PC and the IPSec headend or server, which could be a router, a PIX or a VPN 3000.
You configure most things on the headend, and minimal group name/pw, connection details and username/password (if used) on the client.
See a sample config on:
http://www.cisco.com/warp/customer/471/ios-unity.html